[PATCH AUTOSEL 6.14 642/642] net-sysfs: restore behavior for not running devices

Sasha Levin
2025-05-05T22:39:18Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 75bc3dab4e49b4daccb27ad6ce8ce2fcd253fc1b ]

modprobe dummy dumdummies=1

Old behavior :

$ cat /sys/class/net/dummy0/carrier
cat: /sys/class/net/dummy0/carrier: Invalid argument

After blamed commit, an empty string is reported.

$ cat /sys/class/net/dummy0/carrier
$

In this commit, I restore the old behavior for carrier,
speed and duplex attributes.

Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Marco Leogrande <leogrande@google.com>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Link: https://patch.msgid.link/20250221051223.576726-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/net-sysfs.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index cedbe7d9ae670..474824e88959f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -313,12 +313,13 @@ static ssize_t carrier_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct net_device *netdev = to_net_dev(dev);
- int ret = -EINVAL;
+ int ret;

ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
if (ret)
return ret;

+ ret = -EINVAL;
if (netif_running(netdev)) {
/* Synchronize carrier state with link watch,
* see also rtnl_getlink().
@@ -349,6 +350,7 @@ static ssize_t speed_show(struct device *dev,
if (ret)
return ret;

+ ret = -EINVAL;
if (netif_running(netdev)) {
struct ethtool_link_ksettings cmd;

@@ -376,6 +378,7 @@ static ssize_t duplex_show(struct device *dev,
if (ret)
return ret;

+ ret = -EINVAL;
if (netif_running(netdev)) {
struct ethtool_link_ksettings cmd;

--
2.39.5